| dc.description.abstract | Millions of people in Asia depend on the meltwater of the Himalayan glaciers and snow. They serve as water storage, are used to generate hydropower and act as water source for major rivers in Asia. Due to global warming, the Himalayan glaciers are melting. Besides global warming, light-absorbing particles (LAPs) cause an increase in glacier melt by decreasing the ice albedo. Concentrations of LAPs have increased since the industrial revolution due to an increase in biomass and fossil fuel burning, induced drought and land-use change. The Himalaya is sensitive of LAPs because of the high air pollution at the Indo-Gangetic plain. Much research is done on the influence of LAPs on glaciers, especially for dust and black carbon (BC). However, it is unknown if this air pollution from the Indo-Gangetic plain reaches the high mountain areas of the Himalaya. Therefore, the main aim of this study is to understand if the source of LAPs in high Asia is local or whether the source is pollution from the Indo-Gangetic plain. The second aim of this study is to identify the deposition rate and composition of LAPs for the Langtang Valley in Nepal. To reach the aims of the study a ten-day field work was performed in the Langtang Valley. During the field work, aerosols were collected with two distinct measurement set-ups. The samples collected in the field were analysed with a microscope for the coarse LAPs and with a scanning electron microscope for the fine LAPs. Additionally, to detect possible LAP sources and estimate LAPs outside of the Langtang Valley, satellite images were analysed. Carbon monoxide and the ultra-violet aerosol index data were used to detect dust and black carbon in the atmosphere. Aerosol concentrations were determined to be highest during the pre-monsoon season and the lowest during the monsoon season. In number approximately 85% of the coarse LAPs consisted of transparent silicates. For the fine LAPs aluminosilicates had the highest abundancy. Some BC was measured but in very low concentrations. Therefore, it is suspected that most LAPs come from local sources and not from the Indo-Gangetic plain. | |
